My friend has been so mean to me... A huge dilemma, please help!?

If she was a true friend she would respect your feelings and stop or at least tone it down. It seems she is taking out her misfortune on you by playing the pranks on you. As for girls in public school doing that kind of stuff, they do but normally your friends don't do it to you. You've tried to talk to her, I'd back away for a while and see what happens. If she truly is a friend and cares about you, she'll see what she's doing and make a change. Good luck.